Amy Nathanson, Molly Sharp, Fashina Alade, Eric Rasmussen, and Katheryn Christy, all of The Ohio State University, interviewed and tested 107 children and their parents to determine the relationship between preschoolers' television exposure and their understanding of mental states, such as beliefs, intentions, and feelings, known as theory of mind.

Parents were asked to report how many hours of TV their children were exposed to, including background TV. The children were then given tasks based on theory of mind. These tasks assessed whether the children could acknowledge that others can have different beliefs and desires, that beliefs can be wrong, and that behaviours stem from beliefs.

The researchers found that having a bedroom TV and being exposed to more background TV was related to a weaker understanding of mental states, even after accounting for differences in performance based on age and the socioeconomic status of the parent.

However, preschoolers whose parents talked with them about TV performed better on theory of mind assessments.

"When children achieve a theory of mind, they have reached a very important milestone in their social and cognitive development. Children with more developed theories of mind are better able to participate in social relationships. These children can engage in more sensitive, cooperative interactions with other children and are less likely to resort to aggression as a means of achieving goals," lead researcher Nathanson said.